Amateur career

PCU Dolphins

Castro first played for the PCU Dolphins in the NCAA at the 2003 season as a 5'11" point guard. The Dolphins were not able to clinch a Final Four berth, finishing with a 5-9 record.

Things changed on the 2004 season in which PCU was able to make a turnaround with Castro, Gabby Espinas and Robert Sanz at the helm, denying Letran a back-to-back championship run. Holding the twice to beat advantage, the Dolphins needed an extra game that went into overtime to enter the finals. In the championship series against the University of Perpetual Help, the Dolphins swept the best-of-3 finals series to win their first NCAA championship. Castro played second fiddle to both Espinas who won the League MVP award and Sanz, who won the Finals MVP award.

In the 2005 season, the Dolphins went into another Final Four appearance, and they made short work of Mapua on their way to the Finals were they met Letran once again. The Dolphins won Game 1 behind Castro's game-high 20 points. The Dolphins were beaten by Letran in the next two games as Castro got cold.

In 2006, Castro gave out an all-NCAA team performance as he was named as one of the Mythical 5 members; he and Espinas led PCU to a third consecutive Finals appearance this time against San Beda College. Despite Castro scoring a team-high 16 points, the Dolphins were blown out by the Red Lions on Game 1. Castro's teammates stepped up on Game 2 to force a deciding game. On the third game, with PCU trailing by a point in the dying seconds, Castro passed off the game-winning shot to Beau Belga who missed his jumper to lose the championship for PCU. The Dolphins would be suspended the following year after irregularities on their high school team, thus ending Castro's collegiate career.

Jason Castro was also part of the NCAA-UAAP all star game for 2 times with Gabby Espinas, Rob Sanz, Ian Garrido, Beau Belga, Joel Solis, and Ramon Retaga

Addict Mobile

After a deserving NCAA 2004 Champions and part of the Mythical 5. The Fil-Am Jason Williams Castro was headed to the AMP Mobile Phone team, which he was a back up to LA Tenorio. His PCU teammates Gabby Espinas and Rob Sanz, gave their worth talents to remain in the Philippine Basketball League. They were joined by Ateneo Blue Eagles team, composed of Paolo Bugia, LA Tenorio, Magnum Membrere, and company.

HarbourCentrePort Masters

In this time of Jason Castro's life, he rose to the occasion. Even if he was still a backup to LA Tenorio, he played consistently. He was with Mac Cardona and his former PCU teammates Gabby Espinas, Rob Sanz, Beau Belga and Joel Solis. Castro was slowly becoming a premiere amateur point guard during this time.

Hapee PCU Teeth Masters/ 2 seasons

He then transferred to Hapee PCU. He remained with the team for a season with Gabby Espinas, Rob Sanz, Joel Solis with Mark Moreño and others. Unfortunately, the team was on a slump making them cellar dwellers on the standings. Hapee PCU had a disaster season.

Hapee-PCU Teeth Sparklers

After PCU's championship, Lamoiyan Corporation sponsored the core of that team to participate in the PBL as the Hapee-PCU Teeth Sparklers. The Sparklers entered the Finals against the Harbour Centre Batang Pier and were defeated. Hapee made several more playoff runs but were beaten either by Harbour Centre or by Toyota-Otis (ironically mostly composed of Letran players).

Harbour Centre Batang Pier 3 seasons

When PCU was suspended, Castro transferred to Harbour Centre and won 2 championships with them. After 2 conferences of sterling performances, Castro was named as the PBL 2007 most valuable player.[2] In the next season, Castro and the Batang Pier met Hapee, this time led by Filipino-American Gabe Norwood in both of the season's finals and beat them. Castro was adjudged as the MVP anew, beating Norwood. Proving himself to be a deserving grandslam MVP, he edged Reed Juntilla, Ken Bono, and Gabe Norwood in the race.

SEABA RP Team

In the midst of Jason Castro's third season at Hapee, he was acquired by Junnel Baculli, his coach in PCU, to join the RP team with Marvin Cruz, JC Intal, Ryan Araña, Chad Alonzo, and Beau Belga, with 2 imports. They claimed the SEABA 2006 championship crown.

In the middle of the 2nd season and 3rd season, he was again acquired. He was with Gabe Norwood, Beau Belga, Chad Alonzo, Eugene Tan, Patrick Cabahug, and Jeff Chan. They reached the finals but were unlucky as they lost the SEABA 2007 championship crown. Castro was a MVP contender during this time.

Professional career

Singapore Slingers

Castro signed with the Singapore Slingers during a televised ceremony in May 2008, and was supposed to be become the first Filipino player in the National Basketball League, Australia's top-level professional basketball competition. [3][4] However, about a month before the start of the season, the Slingers withdrew permanently from the NBL citing excessive transport costs to Australia.

Trade Issue

After winning a championship in the All Filipino Cup, Jason Castro might land to another team in the midst or after the Fiesta Conference. Agent/Manager Danny Espiritu said on the interview "Even though he won a championship with Talk 'N Text, I want my player to earn more than what he deserves to play in the PBA. The Talk 'N Text system won't fit his style of game where Jimmy Alapag and some other star studded players make his game down and inconsistent."